The overall goal of the studies described in Project 2 is to improve the outcome of allogeneic marrow transplantation from matched family members in the treatment of lymphoid malignancies, including acute lymphocytic leukemia (ALL), malignant lymphoma and multiple myeloma. In patients with ALL and malignant lymphoma who have not received dose-limiting radiotherapy, the toxicity and efficacy of recombinant alpha interferon given after a preparative regimen of cyclophosphamide and total body irradiation will be evaluated. This study is based on a previous randomized trial which showed that nonrecombinant interferon reduced by 50% the incidence of posttransplant relapse in patients with ALL. In patients with ALL and malignant lymphoma who have received dose-limiting radiotherapy, and attempt will be made to reduce the toxicity of a preparative regimen of carmustine, cyclophosphamide and etoposide with the addition of pentoxifylline. In patients with multiple myeloma the use of marrow transplantation earlier in the course of the disease will be explored and new preparative regimens developed. In "early" patients, including those with poor risk factors after initial response and those with relapsed disease but a low tumor burden, a trial of busulfan, cyclophosphamide and allogeneic marrow transplantation will be performed. In patients with advanced disease, a new treatment approach which combines biochemically targeted radiotherapy using 186Re-HEDP with a standard busulfan/cyclophosphamide regimen will be evaluated.